Title

Electro-Optic Modulation

Problem Scenario

Detection of sidebands in Electro-modulated light.

Broad Question

Can a light beam in the Visible Spectrum be modulated to carry sound or data?

Specific Question

Will transmitting sound through visible light differ with different light colors? Does any one color work better than the others. And can you create Sidebands using this way of Modulation?

Hypothesis

I suspect that the light color/wavelength will generate sidebands.

Graph of Hypothesis

[Not Real Data]
Red	Green	Blue
Ultra - Vloiet Light
122	4	18
255	21	162
	Red LED
198	22	11
255	31	86
White LED
255	255	255
243	252	222
Blue LED
12	0	255
0	0	255
5	34	214
Green LED
123	255	45
47	234	34
Yellow LED
44	213	21
12	255	9

Variables

1. Wavelength bandwidth of the light source and detector.
(meaning can the detector see the wavelength of light from the source)

2. Frequency response of components used.
(meaning what's the range of modulation that can be used before it's outside that of the components where the signal will drop way off)

3. Light diffusion.
(scattering in the atmosphere due to dust and air molecules)

4. The TYPE of modulation (FM verses AM) ...But LEDs produce a specific wavelength/color/frequency which cannot be changed, so I'm stuck with AM, unless I use something other than regular LEDs.

Independent Variable:

Transmitting sound through visible light

Dependent Variable:

Can you create Sidebands using this way of Modulation?

Vocabulary List That Needs Explanation

Diffusion: Scattering in the atmosphere due to dust and air molecules.
LED: Light Emitting Diode
Modulation: The changing of
Bearing: The manner in which one conducts or carries one self,including posture and gestures
RGB Scale: Red Green Blue scale
λ: The symbol for Wavelegenth
v: Velocity of light Aprox. 186,000MPS
F: Frequency

---

---

---

---

General Plan

This project took me a lot of thinking to come up with. First I had to find a bread board, LEDs, Soater, An Oscilloscope, An a

Safety Or Environmental Concerns

There are some Electrical Hazards with minor electrocution
No Environmental Concerns

Resources and Budget Table

Item quantity Price	Name Place
10 30$ 1 Free 1 Free 1 Free	LEDs Radio Shack Sottar Home Circuit board Home Bread Board Home

Data Table

UN-Modulated LEDs in RGB scale.

	WHITE LED
RED	GREEN	BLUE
49	17	204
0	69	254
0	253	67
183	215	183
249	108	20
215	18	35
236	36	36
0	0	0
	BLUE LED
RED	GREEN	BLUE
41	71	253
0	252	252
0	119	162
0	0	0
	RED LED
RED	GREEN	BLUE
196	5	12
0	0	0
	Yellow LED
RED	GREEN	BLUE
228	255	80
0	0	0
	Ultra-Violet LED
RED	GREEN	BLUE
47	0	110
28	28	212
19	16	105
11	42	44
61	3	41
0	0	0

Modulated Light Detecting If There Are Any Sidebands.

	WHITE LED
RED	GREEN	BLUE
48	17	200
0	68	249
0	248	66
179	211	179
244	106	20
211	18	34
231	35	35
0	0	0
	BLUE LED
RED	GREEN	BLUE
40	70	248
0	247	247
0	117	159
0	0	0
	RED LED
RED	GREEN	BLUE
192	5	12
0	0	0
	Yellow LED
RED	GREEN	BLUE
223	250	78
0	0	0
	ULTRAVIOLET LED
RED	GREEN	BLUE
46	0	108
27	27	208
19	16	103
11	41	43
60	3	40
0	0	0

---

---

Background Research

Communications first developed as simply as the Holler. The Holler was the earliest form of verbal communications, now we have telephones, satellites, and radios. The yodel was another form of communication by changing pitch in your voice while yelling into a pipe and on the other end of the pipe there is a bell which emits the sound at a deafening volume for long distance communication. Phones in present time have not changed in about 100 years! If you had an antique phone and plug the phone to the jack it would work!

Citations

Hollerin' History." Ibiblio. Web. 24 Apr. 2012. <http://www.ibiblio.org/hollerin/hollerin.htm>.
How Telephones Work." HowStuffWorks. Web. 25 Apr. 2012. <http://electronics.howstuffworks.com/telephone.htm>.

Detailed Procedure

Using a blank CD as a home-made spectrometer, I captured digital images of the spectral light reflected off the CD from the different LEDs while NOT modulated then used Microsoft Paint to determine the Red-Green-Blue mix of each color band for each LED. This was my baseline. I performed the same experiment again while injecting a 450 Megahertz signal into the LED. No new color band was visible with any of the LEDs.

Diagram

---

---

---

---

---

Results

Results were highly informative... There were no detectable sidebands by the naked eye but there were mathematically proven sidebands that do exist. There would be visibly detectable sidebands if I could modulate in the terahertz but nothing like that is released or exists yet.

Graphs

Depending on the light color there were different bands of light color. We measured the different bands that's why all graphs dont have the same
"Trial Number"

---

---

---

---

Conclusion

The project was unsuccessful, Although I can make it so by getting Transistors that modulate in the terahertz.

---

---

---

---

---

Discussion

Color	Wavelength	Frequency
Red	~ 700–635 nm	~ 430–480 THz
Orange	~ 635–590 nm	~ 480–510 THz
Yellow	~ 590–560 nm	~ 510–540 THz
Green	~ 560–490 nm	~ 540–610 THz
Blue	~ 490–450 nm	~ 610–670 THz
Violet	~ 450–400 nm	~ 670–750 THz
Frequency is velocity (speed of light in this case) divided by the wavelength
F = v / λ
The carrier frequency is in the TeraHertz range (x10^12)
The modulation frequency is in the MegaHertz range (x10^6)
Modulating a carrier frequency (in this case the LIGHT frequency) by another frequency should produce the sidebands at the SUM and the DIFFERENCE frequencies. Therefore, an example if the carrier is at the top of the RED specturm, like at 480 THz (teraHertz), modulating that carrier by 450 MHz (megaHertz) will produce sidebands at 479.999550 THz (still within the RED) and 480.000450 THz (fractionally within the ORANGE).
			Sideband Math looks like this…
			Sideband Freq = Carrier Frequency +/- Modulation Frequency

Benefit to Community and/or Science

There would be no benefit, but the radio is much more effective because radio waves can pass through objects and still keep going.

Abstract

My project is specifically about generating sidebands using modulated light. Although my project was not successful (because I did not slide the decimal point by three places) This project is still able to be successful only if I had a transistor that could modulate in the terahertz, To date no such thing has been released to the public and nothing like that will be released in a while. I did this because this was an idea that was in the back of my head for a while.